Apparatus for releasably connecting well tools to a supporting member



June 27, 1967 G. H. PARDUE 3,327,784

APPARATUS FOR RELEASABLY CONNECTING WELL TOOLS TO A SUPPORTING MEMBER 2Sheets-Sheet Filed Deo. 1l, 1964 6Go/y@ H. Para/ue United States PatentO 3,327,734 APPARATUS FR RELEASABLY CONNECT- ING WELL TLS T A SUPPRTINGMEWER George H. Pardue, Houston, Tex., assignor, by mesne assignments,to Schlumberger Technology Corporation, Houston, Tex., a corporation ofTexas Filed Dec. l1, 1964, Ser. No. 417,619 13 Ciairns. (Cl. 16o-65)ABSTRACT 0F THE DISCLSURE This disclosure is directed to means forsecurely connecting a well tool to a supporting member in such a mannerthat the well tool can be selectively disconnected therefrom should thetool be stuck in -a well bore. In one manner of operation, applicationof a predetermined tension load on the supporting member will disconnectit from the stuck well tool. In another manner of operation, anelectrical signal followed by a lesser predetermined tension load willdisconnect the tool from its supporting member.

Accordingly, as will become apparent, it will be seen that inventionrelates to subsurface tools and is particularly conce-med with apparatusfor releasably suspending such tools from a cable.

In the operation of cable-suspended subsurface tools, such as variousmeasuring and logging devices, subsurface conditions may cause the toolto become stuck. When this occurs, and the tool cannot be dislodged byapplication of a reasonably safe cable tension, it becomes necessary todisconnect the cable from the tool. Preferably, disconnection shouldoccur at or adjacent the tool to facilitate retrieving the cable intact.

A cable that has parted by excess tension is not only itself damaged orlost but frequently interferes with subsequent removal of the tool, asby conventional lishing operations. It has, therefore, becomeconventional to provide a so-called weak-point connection between thecable and tool. This may be done by placing :a weakened member in theline at or adjacent the cable head on the tool to provide a point ofreduced tensile strength. When this is done and the tool becomes stuck,the application of suicient tension on the cable will break theWeakpoint and disconnect the cable from the tool.

Such weak-points must, however, have suicient tensile strength tosupport the static weight of the tool and any loads induced by drag inraising the tool as well as such additional tension as may reasonably beapplied in any effort to dislodge the tool if it becomes stuck.

When the tool is downhole and the cable under tension, the point ofgreatest cable stress will be at or near the surface. For example, if acable having an average tensile strength of 12,000-pounds is used inconjunction with a conventional weak-point having an average tensilestrength of 6,200-pounds and 6,0G0-pounds of cable is within the borehole when the tool sticks, additional tension will probably break thecable at or near the surface before the weak-point can be loaded beyondits tensile strength. Thus, a conventional weakpoint may becomeinoperable if the tool becomes stuck at a substantial depth. Moreover,this particular problem with conventional weakpoints tends to increasewith operating depth since the footage which may be handled by the cablewinch is greatly dependent upon cable diameter and, as diameter isreduced to increase footage, average tensile strength is sacrificed.

Further, the tension at which a conventional weakpoint will break mustnecessarily be empirically deter- ICC mined. Itis therefore necessary toactually break representative samples from each lot of weak-pointsmanufactured, average the tensile force required to break them and takethat average, plus or minus the deviation encountered (typically aboutI'ive to ten percent) as the average tensile strength of each weak-pointin the lot. Thus, in the hypothetical example just given, that weakpointmight actually break several hundred pounds above or below 6,200-pounds.As a result, unless great pains are taken, there is always anuncertainty about the amount of cable tension that may be safely appliedin attempting to dislodge a stuck tool, as well as the .tension actuallyrequired to break the weak-point.

If in the course of tensioning the cable to break a conventionalweak-point, the cable becomes key-seated (i.e., cuts into, and becomesbound by, the wall of a bore hole) as sometimes occurs in soft walledbore holes, before suiiicient tension is developed to either dislodge astuck tool or break the weak-point, release of the cable adjacent thetool is frustrated. When this occurs, the cable tension must beincreased until the cable itself breaks. Such a break will be usually ator near the surface, but may be at a point of latent cable damagebetween the surface and the key-seat.

According to the present invention, release apparatus is provided forselectively releasing the cable by the application of any desiredtension Ibetween minimum and maximum predetermined values, using releasemeans which may be electrically operable from the surface, or simply bythe application of a precisely predetermined maximum tension load.

More specifically, this invention is characterized by a mechanicallydisengageable member affording a releasable connection. Such a membermay be provided by a collet having a plurality of radially disposeddepending fingers terminating in angulated lugs which are securelygripped between movable opposed abutments within a cable head. Anelectrically releasable latching device retains one abutment normallyengaged with one side of the collet lugs. The other abutment is normallypositioned against the opposite side of the collet lugs and pre-loadedspring means are provided to prevent withdrawal of this other abutmentunless and until a precisely predetermined tension is applied. Thus,cable release may occur selectively either when the latched abutment isreleased from engagement with the collet lugs in response to an electricsignal or when the pre-loaded abutment is released from engagement withthe collet lugs in response to application of a cable tension sufficientto overcome the pre-load springs.

More particular understanding of the invention may be had from thefollowing description of one embodiment thereof which has beenillustrated in the appended drawings, wherein:

FIGURE l is an elevation view partly cut-away.

FIGURE 2 is a section view taken along line 2 2 of FIGURE 1.

FIGURE 3 is a section view tken along line 3 3 of FIGURE 2.

FIGURE 4 is a partial section showing the lower abutment in unlatchedcondition.

FIGURE 5 is a partial section showing the lower abutment moveddownwardly from the collet lugs and the collet being withdrawn.

FIGURE 6 is a partial view showing the pre-loaded abutment and colletbeing withdrawn from locking engagement with the lower abutment.

FIGURE 7 is a partial view showing the pre-loaded abutment in completelywithdrawn position, and the collet being released.

In the illustrated embodiment of this invention, as shown in FIGURE 1,-a winch carries a cable 11, which may conveniently include a pluralityof electrical conductors 12. In operation, cable 11 typically passesfrom winch 10 under sheave 13 and over sheave 14, which is equipped witha tensiometer 15. After passing over sheave 14, cable 11 is connected toa cable head 16 from which a tool 17 may be suspended in a well bore bya threaded adapter 18.

As shown in FIGURE l, cable head 16 includes a cylindrical housing 10adapted to threadably receive adapter 18 at its lower end and toslidably receive a so-called boot 20 at its upper end. With continuedreference to FIGURE 1, it will be seen that the central load supportingmember 21 of cable 11 is secured to the upper end of a shank 22 by meansof swaged socket 23. Then, as best seen in FIGURE 2, shank 22 extendscoaxialiy into housing 19 with its lower end being formed into a collet24 comprised of radially disposed depending fingers 25, each havingoutwardly facing angulated lugs 26.

With continued reference to FIGURE 2, it will be seen that collet lugs26 are securely engaged between an upper abutment 27 and a lowerabutment 28 which abutments are carried by and operable within acylinder 29 received in housing 19. Cylinder 29 is supported in housing19 by securing its flanged lower end 33 between internal shoulder 34 ofhousing 19 and the upper face 35 of plug 30. In turn, plug 30 is held bythreading adapter 18 into the lower end of housing 19 until adapter 18securely engages the lower end 32 and intermediate shoulder 31 of plug30. At its upper end, cylinder 29 is sealed4 by a exible bellows 36 theupper and lower ends of which are respectively secured to shank 22 andcylinder 29.

Intermediate the ends of cylinder 29, its bore is reduced in diameter toprovide an internal lannular shoulder 37. A collet sleeve 38 is slidablydisposed around a reduced portion of shank 22 and collet 24. Lateral pin39 in a slot at the upper end of sleeve 38 prevents the sleeve 38 fromrotating relative to shank 22. Sleeve 38 has an enlarged lower end witha peripheral flange 40 which rests on shoulder 37 and an internallyformed surface forming abutment 27 which engages the outer surfaces ofcollet lugs 26. A plurality of stacked Belleville washers 42 aredisposed around the collet sleeve 38 and carried by the peripheralflange 40. A sleeve 43 is slidably disposed around the collet sleeve 38and shank 20 and engages the upper end of the washer stack 42. Anexternally threaded adjusting nut 44 threadably engaged within theuppermost end of the bore of cylinder 29 is utilized to hold the washerstack 42 compressed and to urge ange 40 of the collet sleeve 38downwardly against the upper side of shoulder 37 with a force ofpredetermined magnitude.

A cup-type latch housing 45 is disposed Within the bore of cylinder 29with its upper closed end engaged against the underside of shoulder 37.A latch carrier body 46 is slidably received in housing 45 and has areduced-diameter frusto-conical portion which forms abutment 28projecting upwardly from its upper end. Abutment 28 extends through anopening in the closed end of latch housing 45 and normally engages theinner surfaces of collet lugs 26. A plurality of depending fingers 48are pivotally suspended within circumferentially spaced longitudinalslots in the annular body 46. At the lower free end of fingersV 48,inwardly extending recesses 49 are provided to engage the inward sideyof a plurality of ball members 50 loosely received within holes throughthe side of body 46. Housing 45 has annular recesses 51 in which theoutward side of the ball members 50 are normally received to secure theannular body 46 in its uppermost position.

Below body 46, a solenoid 52 is mounted within the housing 45 andincludes a solenoid coil 53 having an upper pole piece 54. A tubularnon-magnetic plunger 55 is mounted on an armature 56 in the positionillustrated. Plunger 55 extends upwardly into the hollow interior ofbody 46 and has an enlarged non-magnetic upper portion 57. A pluralityof balls 58 are loosely mounted in recessed porons of the enlargedplunger portion 57 and held in this position by a follower sleeve 59which is biased upwardly by a light spring 60.

Each of the balls 58 are suitably positioned to be normally engagedagainst the inner surfaces of an offset tip portion 61 of the pivotedfingers 48 so long as the solenoid 52 is de-energized. Thus, so long aseach set of balls 50 and 58 remains laterally opposite one another, thefree ends of each of the pivoted fingers 48 are held therebetween toprevent body 46 from shifting downwardly, thereby maintaining abutment2S firmly engaged against the inside of collet lugs 26.

Electrical circuitry suitable for energizing solenoid 52 is readilyprovided by electrical conductor lead 62 taken from the lower end of oneof conductors 12 which normally extend between tool 17 and itsassociated surface equipment. When assembled, cylinder 29 is preferablyhermetically sealed and oil-filled to achieve maximum protection fromcorrosive well-liuids, with the environmental pressure differentialbeing compensated by the dilerential bellows 36.

To prevent inadvertent cable release by accidental actuation of solenoid52, las hereinafter explained, a safety is provided. This safety takesthe form of a weak-point designed to support a minimum load, e.g., thestatic load of a freely supported tool. Such weak-point comprises areplaceable rod 63 of non-magnetic material threadably connected at oneend to shank 22 and extended through plunger 55 where it is connected tohead 16 through plate 64 and housing 45 with a nut 65. Rod 63 has areduced, weakened cross-section at 66 so as to break at, say LOGO-poundstension plus or minus 10%. As best seen in FIGURE 2, so long as lugs 26are engaged by abutments 27 and 28, no tension is applied to the rod 63and the load is transmitted from the collet to abut* ment 27. However,when lugs 26 are released, the full load is immediately transferred torod 63. If the load is above the minimum, rod 63 will break at 66.

In the event a tool carried from head 16 becomes stuck, cable 11 may bereleased from the head in either of two ways. If it is desired torelease the cable 11 at a reduced tension, solenoid 52 is firstelectrically energized, e.g. by passing energizing current to solenoid52 through that one of conductors 12 in the cable 11 which is connectedto conductor 62. When energized, armature 56 is pulled upwardly towardupper pole piece 54 to elevate the enlarged plunger portion 57. As theplunger portion 57 moves up, balls 58 roll upwardly along the innersurfaces of the latch lingers 48 from their position shown in FIG- URE 2to the position shown in FIGURE 4. Once the inner balls 58 have clearedthe offset .tip portion 61 of lingers 48, the fingers are free to swinginwardly a suicient radial distance to permit the outer balls 50 to alsomove inwardly and roll out of the annular recesses 51. It will beappreciated, of course, that once the inner balls 58 have moved intotheir position as shown in FIG. 4, the body 46 is held in its uppermostposition only by the biasing effect of spring 67.

Accordingly, whenever only a slight amount of tension is applied tocable 11, the upward pull on shank 22 will force the collet fingers 25to contract as the upper abutment 27 cams the collet lugs 26 inwardly.As the collet lugs 26 move inwardly, the camming action of the innerfaces of the lugs on the frusto-conical surface of the lower abutment 28will shift body 46 downwardly.

Once the body 46 has moved downwardly only a slight distance, the lowerabutment 28 no longer restrains the collet lugs 26; and the lingers 25are then retracted suiiiciently to free the lugs from the upper abutment27 as shown in FIGURE 5. It will be appreciated that once the lugs 26are free of abutment 27, the full load on the cable 11 is then appliedto the weak-point or rod 63. Once the cable load has reached thepredetermined design tensile strength of the weakened portion 66 of rod63,

the weakened portion will fail. Then, the shank 22 and all elementsthereabove on the shank will be pulled out of the housing 19. As theshank 22 moves upwardly, the flexible bellows 36 are, of course, broken.As seen in FIGURE l, the boot 20 is only splined to the housing 19 andwill easily pull out of the housing.

If the electrical system should be inoperative or should there be someother reason for not utilizing it, the cable 11 can also be releasedmechanically by pulling on the cable. In this instance, sufficienttension must first be applied to overcome the oppositely directedpredeter mined load applied by the Belleville washers 42. Once thispredetermined load has been equaled, the upper abutment 27 will shiftvery slightly upwardly away from flange 37. As additional tension isapplied on the cable 11, the additional force will then be imposed onthe weak-point 63 until the added force has reached the level necessaryto break the weakened portion 66. Once this weakened portion 66 breaks,the additional force is suddenly transferred to the Belleville washers42 which then further compress a sufficient distance to allow collet 24and flange 40 to move upwardly. Once the collet fingers 25 have movedupwardly a short distance, the inner surfaces of the collet lugs 26 areno longer in contact with the lower abutment member 28 and the colletlingers 25 are free to contract and slip upwardly into collet sleeve 38.When this occurs, cable 11, shank 22, and collet 24 may be withdrawnfrom head 16 in the manner shown in FIG- URES 6 and 7.

Among the several advantages of this invention is the capacity of therelease apparatus to withstand jarring without Ipremature release. Thisis because freeing of lugs 26 by releasing balls 50 requires that body46 and enlarged plunger portion 57 move toward each other. Sincejarring, whether from above or below, will produce forces acting in onlyone direction, this required counter-movement of body 46 and theenlarged plunger portions 57 will not occur. Additionally, the viscosityof the oil within cylinder 29 will dampen any movement of body 46 andplunger portion 57.

It should be noted that the springs 60, 67 and 69 will aid in holdingthe members with which they are engaged in position to maintain theapparatus latched. Moreover, these springs 60, 67 and 69 will permit theelectrical release system to be tested before the apparatus is loweredinto a well bore since once the solenoid 52 is deenergized, the springswill restore their respective members to their normal positions. It willalso be appreciated that spring 60 and ball follower 59 will ensure thatballs 58 are free to roll rather than having to slide upwardly. Thus,the load that the solenoid 52 must operate against is minimized byencountering rolling, rather than sliding, friction.

It will be appreciated that with the weak-point 63 the release force canbe much more precisely known than with conventional systems since,unlike conventional mass-produced weak-points, the weak-point 63 will bedesigned to support only a few hundred pounds. By employing theapparatus of the present invention in the previous example, theweak-point 63 can be designed to have an average tensile strength ofL200-pounds and a predetermined load of 5,000-pounds applied to theBelleville washers 42. Thus, assuming the margin of error in determiningthe breaking strength of the weak-point 63 to be the release point willvary only 1Z0-pounds above or below the design release point of6,200-pounds as contrasted with the Wide range typical of conventionalmass-produced weak-points designed for higher loads.

Devices embodying this invention might take various forms and may employa variety of equivalent means. Thus, the collet means might be replacedwith other connection means; the washer stack might be replaced with aspring or other pre-load means; a tool might be connected directlyrather than through a cable head; a tool might employ only theelectrically operative release feature; or, when non-electrical cable`is used a tool, might employ only the yieldable pre-loaded releasefeature.

Thus, the scope of the invention taught herein is much broader than theone embodiment illustrated and described, such description andillustration being given solely to facilitate further understanding ofthe invention by those skilled in the art to which it pertains.Accordingly, the invention will readily admit of other equally effectiveembodiments all of which are intended to be within the scope of theappended claims.

I claim: 1. In a subsurface tool adapted to -be suspended from a cableextending to the surface, apparatus operable from the surface forreleasing said tool from a cable, said apparatus comprising:

rst and second co-engaging companion members respectively connected tosaid tool and adapted for connection to a cable; means for releasablyconnecting said companion members including stop means on one of saidcompanion members .arranged and adapted to engage the other of saidcomp-anion members for constraining said other companion member, saidstop means being movable from a normal position in engagement with saidother companion member for connecting said companion members to anotherposition for disconnecting said companion members; means for retainingsaid stop means in said normal position and operable from the surfaceand through a cable to release said stop means for movement to `saidother position; and means for releasably securing said companion membersincluding a breakable linking member normally fastening said companionmembers together. 2. As a sub-combination for use in a subsurface tooladapted to Abe suspended from a cable extending to the surface,apparatus operable from the surface for releasing such a tool from acable, said apparatus comprising:

lirst and second `co-engaging compani-on members respectively adaptedfor connection to a tool and a cable; means for releasably connectingsaid companion members including firs-t and second stop means on onesaid companion members to connecting said companion members;

force-applying means retaining said first s-top means in said normalposition applying means being directed force applied through said secondcompanion member in excess of said predetermined magnitude to overcomesaid force-applying means and move said rst stop means to said otherposition. 3. In a subsurface tool adapted to be suspended from a ca'bleextending to the surface, apparatus operable from the surface forreleasing said tool from a cable, said apparatus comprising:

first and second co-engaging companion members respectively connected tosaid tool and adapted for connection to a cable; means for yreleasablyconnecting said companion members including first and second stop meanson one of said companion members for constraining the other of saidcompanion members, said rst stop means lbeing movable independently ofsaid second stop means from a normal position in engagement with saidother companion member for connecting said companion members to anotherposition for disconnecting said companion members;

and spring means retaining said first stop means in said normal positionand urging said first stop means toward said second stop means with aspring force of predetermined magnitude, said spring means beingyieldable in response to an oppositely-directed force applied throughsaid second companion member in excess of said predetermined magnitudeto overcome said spring force and move said first stop means to saidother position.

7. In a subsurface tool suspended from a cable extending to the surface,apparatus operable from the surface for releasing said tool from saidcable, said apparatus comprising:

first and second co-engaging companion members respectively connected tosaid tool and said cable; means for releasably connecting said companionmembers including first and second movable stop means 4. In a subsurfacetool adapted to be suspended from Aa cable extending to the surface,apparatus operable from the surface for releasing said tool from acable, said apparatus comprising:

first and second tro-engaging companion members erespectively connectedto said tool and adapted for connection to a cable; means for releasablyconnecting said companion rnembers including first and second stop meanson one 0n one of Said Companion members arranged and of said companionmembers -ior constraining the adapted to engage the other of saidcompanion memother of said companion members, said first stop bers forconstraining Said other Companion rnern' means being movable from anormal position in ber, eeen of Said Stop IneanS being independentlyengagement with said other companion member for movable from a norrnnlPosition in engagement With connecting said companion members to anotherposi- Said other Companion member for Connecting Said tion fordisconnecting Said Companion members; companion members to anotherposition for disconspring means retaining said first stop means in saidneetlng Sad Companion rneInberS;

normal position and urging said irst stop means toand first and secondmeans for respectively retaining ward said second Stop Imeans with aforce of presaid first and second stop means in their said normaldetermined magnitude, said spring means being yield- Positions, each ofSeid retaining Ineens being Selecable in response to anopposite1y-directed force on tively operable from the Surface andthrough Said said first stop means and in eXeeSS of Said predetefcableto release their associated one of said first and mined magnitude -tomove said first stop means to Second SioP means for independent movementto said other position; their said other positions.

and means for releasably Securing Said eompanion 8. In a subsurface tooladapted to be suspended from a cable extending to the surface, apparatusoperable from the surface for releasing said tool from said cable, saidapparatus comprising:

first and ysecond co-engaging companion members remembers including abreakable member normally fastening said companion members together.

5. in a subsurface tool adapted t-o be suspended from a cable extendingto the surface, yapparatus operable from the Surface for releasing Saidtool ,from a cable, said ap spective'ly connected to said tool andadapted for paratus comprising: connection to a cable;

rst and Seeond no engaging Companion members 1.e means f or releasablyconnecting said companion memspectively connected to said tool andadapted for conbers meludmg first and Second movable Stop Ineens nectionto acable; on one of said companion members arranged and .means forreleasably Connecting said Companion meuk adapted to engage thel otherlof said companion bers including first `and second stop means on one ofmembers for constraining Said other. compamon said companion membersarranged .and adapted to member @ash of 'Sad Stop mean belngIndependent' engage and constrain the other of said companion 1y movrblfrom a non nal Posltlon 1n engagement members, said first stop meansbeing movable indewith Sad other Compamon member for ,Connectingpendently of said second stop means from a normal Sald cofflpamqnmember? to another Posltlon for 15" position in engagement with saidother companion connectmg Sad compamon memlefs member for ConnectingSaid companion members to first and second means for respectivelyretaining said another position for disconnecting said companion rst,and Second Stop means m their Sall normal members; positions, each ofsaid retaining means being selecmeans for retaining Said rst stop meansin Said normal tively operable from the surface and through a cableposition; to release their associated one of said first and second stopmeans for independent movement to their said other positions; and meansfor releasably securing said companion members including a breakablelinking member normally fastening said companion members together. 9. Ina well tool adapted to be suspended in a Well bore from a cable havingelectrical conductor means and extending to the surface of the ground,selectively-operable release apparatus comprising:

first and second co-engaging companion members respectively connected tosaid tool` and adapted for connection to such a cable; means forreleasably connecting said companion memand means responsive to anelectrical sign-al `for disabling said retaining means and freeing saidfirst stop means for movement to said other position to disconnect saidcompanion members. 60 6. In a subsurface tool adapted to be suspendedfrom a cable extending to the surface, apparatus operable from thesurface for releasing said tool from a cable, said apparatus comprising:

first and second co-engaging companion member re- 6 respectivelyconnected to said tool and adapted for connection to a cable; means forreleasably connecting said companion members including first and secondstop means on one of bers including first and second movable stop meanssind Companion 'rnernberS arranged 'and adapted 'EO on one of saidcompanion members arranged and engage and constrain the other of saidcompanion adapted to engage the other of said companion memmembers,said'first stop means being movable from bers for constraining saidother companion member, a normal position in engagement with said othereach of said stop means being movable from a norcompamon member forconnecting said companion mal position in engagement with said other eompanion member for connecting said companion memand means for releasablysecuring said companion members to another position for disconnectingsaid combers including a breakable linking member normally panionmembers; fastening said companion members together. first means forretaining said first stop means in said 12. In a subsurface tool adaptedto be suspended from normal position electrical means operative from thea cable extending to the surface, apparatus operable from surface andthrough such a cable to actuate said first the surface for releasingsaid tool from said cable, said retaining means to a position forselectively releasing apparatus comprising: said first stop means formovement to said other first and second co-engaging companion membersreposition; and spectively connected to said tool and said cable; springmeans retaining said second stop means in said l0 means for releasablyconnecting said companion memnormal position for urging said second stopmeans bers including first and second movable stop means toward saidfirst stop means with a force of a preon one of said companion membersarranged and determined magnitude, said spring means being yieldable inresponse to a force applied through said second companion member inexcess of said predetermined magnitude to overcome said spring force andselectively move said second stop means to said other position.

adap-ted to engage the other of said companion members for constrainingsaid other companion member, each of said stop means being movable froma normal position in engagement with said other companion member forconnecting said companion members to another position for disconnectingsaid companion members;

latch means for retaining said first stop means in said normal positionand including means responsive to an electrical signal for disablingsaid latch means and moving said first stop means to said otherposition;

and spring means for retaining said second stop means in said normalposition and including means respon- 10. In a subsurface tool adapted tobe suspended from a cable extending to the surface, apparatus -operablefrom the surface for releasing said tool from a cable, said apparatuscomprising:

first and second co-engaging companion members respectively connected tosaid tool and adapted for connection to a cable; means for releasablyconnecting said companion members including first and second stop meanson one of said companion members arranged and adapted to engage theother of said companion members for sive to a tension of predeterminedmagnitude on said other companion member for disabling said spring meansand moving said second stop means to said constraining said othercompanion member, each of said stop means being independently movablefrom a normal position in engagement with said other other position. 13.As a sub-combination for use in a subsurface tool adapted to besuspended from a cable extending to the companion member for connectingsaid companion Surface, apparatus operable from the surface forreleasmembers to another position for disconnecting said ing such at-ool from such a cable, said apparatus comcompanion members; prising:latch means for retaining said lirst stop means in said first and secondco-engaging companion members renormal position and operable from thesurface and spectively adapted for connection to a tool and a through acable to free said first stop means for cable; movement to said otherposition; means for releasably connecting said companion memand springmeans retaining said second stop means bers including first and secondmovable stop means in said normal position for urging said second stopmeans toward said first stop means with a force of predeterminedmagnitude, said spring means being yieldable in response to a forcedirected away from on one of said companion members arranged and adaptedto engage the other of said companion members for constraining saidother companion member, each of said stop means being movable from anormal said first stop means acting on said second stop means and inexcess of said predetermined magnitude to move said second stop means tosaid other position. 11. In a subsurface tool suspended from a cableextending to the surface, apparatus operable from the surface forreleasing said tool from said cable, said apparatus comprising:

first and second co-engaging companion members respectively connected tosaid tool and said cable; means for releasably connecting said companionmembers including first and second movable stop means on one of saidcompanion members arranged and adapted to engage the other of saidcompanion members for constraining said other companion member, each ofsaid movable stop means being movable from a normal position inengagement with said other companion member for connecting saidcompanion members to another position for disconnecting said companionmembers; latch means for retaining said first stop means in saidposition in engagement with said other companion member for connectingsaid companion members to another lposition for disconnecting saidcompanion members;

latch means for retaining said first stop means in said normal positionand including means responsive to an electrical signal for disablingsaid latch means and moving said first stop means to said otherposition;

spring means for retaining said second stop means in said normalposition and including means responsive to a tension of predeterminedmagnitude on said other companion member for disabling said spring meansand moving said second stop means to said other position;

and means including a breakable member of predetermined strength fornormally connecting said companion members independently of said stopmeans.

References Cited UNITED STATES PATENTS normal position and operable fromthe surface and herman 2941686 through said cable to free said firststop means for agan 2,296,397 9/1942 Mhlbach 294-86.18 movement to saidother position, spring means retaining said second stop means in said2,618,345 11/1952 Tucker 166123 normal position for urging said secondstop means 2,778,428 1/1957 Baker et al 166*125 toward said first stopmeans with a force of prede- 2,872,238 2/1959 Damn 294-8618 terminedmagnitude, said spring means being yield- 3,203,531 9/ 1965 Tamplen166-125 able in response to a force acting on said second stop means andin excess of said predetermined magnitude CHARLES E' O CONNELL PrmaryExammer' to move said second stop means to said other position; D. H.BROWN, Assistant Examiner.

5. IN A SUBSURFACE TOOL ADAPTED TO BE SUSPENDED FROM A CABLE EXTENDINGTO THE SURFACE, APPARATUS OPERABLE FROM THE SURFACE FOR RELEASING SAIDTOOL FROM A CABLE, SAID APPARATUS COMPRISING: FIRST AND SECONDCO-ENGAGING COMPANION MEMBERS RESPECTIVELY CONNECTED TO SAID TOOL ANDADAPTED FOR CONNECTED TO A CABLE; MEANS FOR RELEASABLY CONNECTING SAIDCOMPANION MEMBERS INCLUDING FIRST AND SECOND STOP MEANS ON ONE OF SAIDCOMPANION MEMBERS ARRANGED AND ADAPTED TO ENGAGE AND CONSTRAIN THE OTHEROF SAID COMPANION MEMBERS, SAID FIRST STOP MEANS BEING MOVABLEINDEPENDENTLY OF SAID SECOND STOP MEANS FROM A NORMAL POSITION INENGAGEMENT WITH SAID OTHER COMPANION MEMBER FOR CONNECTING SAIDCOMPANION MEMBERS TO ANOTHER POSITION FOR DISCONNECTING SAID COMPANIONMEMBERS; MEANS FOR RETAINING SAID FIRST STOP MEANS IN SAID NORMALPOSITION; AND MEANS RESPONSIVE TO AN ELECTRICAL SIGNAL FOR DISABLINGSAID RETAINING MEANS AND FREEING SAID FIRST STOP MEANS FOR MOVEMENT TOSAID OTHER POSITION TO DISCONNECT SAID COMPANION MEMBERS.